1. Field
The disclosed embodiments are related to cooling mechanisms. More specifically, the disclosed embodiments are related to a fan assemblies.
2. Related Art
Many large corporations are increasing their use of data centers as they develop new ways of using information systems to optimize their business operations. Furthermore, the increasing popularity of the Internet and cloud-based computing is fueling demand for ever-larger data centers that can store and process enormous volumes of information. Consequently, in an effort to increase the performance of servers in data centers, system designers are equipping servers with more devices (i.e., processors, networking devices, peripheral devices, power converters, and other devices). As the number of devices increases, the heat produced by the devices can cause the internal temperature of a server to rise to a point where the devices can be damaged or can experience significantly shortened lifespans. To mitigate these problems, servers are typically equipped with one or more fans to force a flow of air through the server to remove internal heat from the server.
Some servers produce so much heat that the flow of air produced by fans in traditional arrangements is insufficient to control the internal temperature of the server, some servers include multi-fan assemblies that are configured to generate a high-volume airflow using two fan trays in tandem. For example, FIG. 1A illustrates a typical tandem fan assembly 100, which includes fan trays 102-104 oriented in series and separated by a distance 106. The fans in fan trays 102 and 104 drive a flow of air in direction 108, so that air that exits an outlet face of fan tray 102 enters an inlet face of fan tray 104.
Although they increase overall airflow, fan assemblies (such as tandem fan assembly 100) may not produce an optimal airflow pattern because the airflow that exits the outlet face of fan tray 102 is not perpendicular to the inlet face of fan tray 104. More specifically, the airflow exits the outlet face of fan tray 102 in a turbulent twisting motion (i.e., with an approximately helical velocity vector). Thus, instead of hitting the fan blades of fan tray 104 in the orientation for which the fans in fan tray were optimized (i.e., perpendicular to the face of fan tray 104), the airflow hits the fan blades at suboptimal angles. Consequently, the combination of fan tray 102 and fan tray 104 may produce slightly more airflow pressure than a single fan tray, but does not produce twice the airflow pressure of a single fan tray.
In an effort to increase the efficiency of fan assemblies such as the illustrated fan assembly, designers have included airflow-straightening elements between the fan trays. Airflow-straightening elements can straighten and re-orient the turbulent flow of air as it passes between the fan trays to ensure that the air hits the blades of fan tray 104 at an angle closer to the optimal angle. For example, FIG. 1B illustrates an exemplary tandem fan assembly 110 with an airflow-straightener 116. Tandem fan assembly 110 includes fan trays 112 and 114 oriented in series, and includes an airflow-straightener 116 between fan trays 112-114. The fans in fan trays 112 and 114 drive a flow of air in direction 118, such that air that exits an outlet face of fan tray 112 flows through airflow-straightener 116 before entering an inlet face of fan tray 114. Airflow-straightener 116 can include a set of fins for straightening the flow of air. For example, FIG. 1C presents a honeycomb-shaped fin 122 in an airflow straightener 120.
Unfortunately, because the fans can consume a significant portion of a server's overall power, and because a limited number of fan assemblies can be mounted on a given server, many servers cannot be kept sufficiently cool even using these existing multi-fan assemblies.